1. Field of the Invention
This invention relates to conversion of digital video signals from a conventional format to a high-definition format and/or vice versa.
2. Description of the Prior Art
High definition digital video is becoming increasingly popular, and common formats for the video signals are:
SMPTE 240M format, which is characterised by 1125 lines, 60 field/s, 2:1 interlace, with a 16:9 aspect ratio and 1920.times.1035 active pixels per frame; and PA1 European HDTV format, which is characterised by 1250 lines, 50 field/s, 2:1 interlace, with a 16:9 aspect ratio and 1920.times.1152 active pixels per frame. PA1 CCIR 601 525-line format, which is characterized by 525 lines, 60 field/s, 2:1 interlace, with a 4:3 aspect ratio and 720.times.486 active pixels per frame; PA1 CCIR 601 625-line format, which is characterised by 625 lines, 50 field/s, 2:1 interlace, with a 4:3 aspect ratio and 720.times.576 active pixels per frame; PA1 4fsc 525 D2 format, which is characterised by 525 lines, 60 field/s, 2:1 interlace, with a 4:3 aspect ratio and 768.times.486 active pixels per frame; and PA1 4fsc 625 D2 format, which is characterised by 625 lines, 50 field/s, 2:1 interlace, with a 4:3 aspect ratio and 948.times.576 active pixels per frame.
More and more material is being originated in these formats for processing and/or distribution in them. However, there is obviously a great bulk of material which has been originated, or still needs to be originated, in conventional definition format, and there is a desirability to be able to up-convert such material to high definition format so that it can be distributed in high definition format. Furthermore, material which is now being originated in high definition that it can be integrated with other conventional definition material and/or so that it can be distributed in conventional definition format. Examples of conventional definition digital formats are:
(Although 60 field/s is mentioned above as the field rate for the 525-line formats, strictly the field rate should be 59.94 field/s. Nevertheless, for simplicity in this specificatin the value of 60 field/s is used.)